﻿ Odd numbers — Math18

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# Odd numbers

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## What are the odd numbers?

Odd numbers are those numbers that are not multiples of 2, therefore, an odd number is not divisible by 2. An odd number cannot have decimals.

Another alternative to check if a number is odd is when the last digit ends in 1, 3, 5, 7 or 9.

Mathematically it is possible to obtain an odd number using the following equation:

Odd number = 2n + 1

Where n is any integer.

Odd numbers form an arithmetic progression, with a difference of 2, this means that adding or subtracting 2 from an odd number gives you another odd number.

Note: Negative numbers can also be odd.

## Operations with odd numbers

### Add and Subtract to get an odd number

When adding or subtracting an even number with an odd number the result is an odd number.

even number + odd number = odd number
odd number + even number = odd number

### Multiplication to obtain an odd number

When you multiply an odd number by an odd number, the result is an odd number.

odd number x odd number = odd number

## Odd numbers from 1 to 100

The table shows the odd numbers in blue background.

 1 3 5 7 9 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100

The odd numbers from 1 to 100 are: 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97 and 99.

It is possible to observe from the table that every odd number has as last digit the number 1, 3, 5, 7 or 9 and every number with white background color corresponds to even numbers.

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Arithmetic Tutorials